/Engine/Source/Editor/UMGEditor/Public/DesignerExtension.h
Called every time a element the designer can extend is selected.
virtual void ExtendSelection ( const [TArray](API\Runtime\Core\Containers\TArray)< [FWidgetReference](API\Editor\UMGEditor\FWidgetReference) > & Selection, [TArray](API\Runtime\Core\Containers\TArray)< [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [FDesignerSurfaceElement](API\Editor\UMGEditor\FDesignerSurfaceElement) > > & SurfaceElements )